All test equipment requires a 30 minute warm-up period to ensure accurate
performance.
In the following test setup, cables are designated as solid lines and direct
connections are designated as dashed lines.
This adjustment uses a power meter and a spectrum analyzer to measure the absolute RF output power of the UUT. Correction factors are calculated and downloaded to maintain accurate power levels over the full frequency range of the UUT.
The internal attenuator in the ESG can be either an electronic or mechanical attenuator. The electronic attenuator consists of 7 distinct attenuator sections (10A, 5A, 40A, 20A, 40B, 10B, and 5B). The mechanical attenuator consists of 5 distinct attenuator sections (60, 20, 40, 10, and 5). These sections are internally connected in the proper combination to give attenuation values from 0 dB to 130 dB, in 5 dB steps.
This adjustment procedure is divided into two main functions: power flatness (0 dB ) and step attenuator adjustments (5 to 130 dB). For the 0 dB setting, it adjusts power level for both normal and low noise floor modes of operation; each mode has separate correction factor arrays. For the 5 to 130 dB step attenuator settings, it determines a correction factor required to compensate for variances in the actual step attenuator performance. Absolute power measurements are made with a power meter and power sensor that are traceable to the National Institute of Standards and Technology. The power meter is used over the 0 dB to 30 dB attenuator range. The remaining step attenuator range is covered with a spectrum analyzer (PSA).
Power Meter Measurements (Electronic and Mechanical)
The UUT flatness cal arrays are defaulted to 0. The UUT amplitude is set to +10 dBm (typically), and the step attenuator is set to zero dB. Absolute power measurements are made at a series of frequency points from 100 kHz up to the UUT maximum frequency and correction values are stored in the UUT. The step attenuator is then set to 5 dB and the power measurement is repeated at each frequency point. The process is repeated in 5 dB steps for attenuator settings up to 30 dB at each frequency point.
Attenuator PSA Measurements
A spectrum analyzer (PSA) and an amplifier are used to measure the attenuator pads from 35 dB to 130 dB. The PSA makes a reference power level measurement with the UUT set to +7 dBm (typically) and the step attenuator set to 30 dB. The trace is set to the reference level of the PSA. The marker delta function is turned on and the UUT attenuation is increased. The marker delta value, nominal marker delta, and the 30 dB correction factor are used to calculate the attenuator steps correction factors. For frequencies ≤ 3000 MHz, the internal pre-amp of the PSA is turned on. For frequencies >3000 MHz the PSA pre-amp is turned off and an external microwave amplifier is inserted in the RF path. Also for frequencies >3000 MHz, the PSA has an internal YIG tuned filter in the RF path; however, this filter is bypassed for this adjustment. If a spectrum analyzer spurious signal is detected at low power levels, the measurement frequency is shifted to avoid the spurious signal.
|
Test Equipment |
Recommended Model |
|
Power Meter |
E4418A, E4418B, E4419A or E4419B |
|
Power Sensor |
E9304A |
|
Spectrum Analyzer
|
E4440A, Opt 1DS, Opt 123 for ESG > 3 GHz |
|
Microwave Amplifier |
Agilent 83006A (0.01 to 26.5 GHz) for ESG >
3 GHz |
|
Power Supply |
87421A |
Connections and Setup Procedures
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|
All test equipment requires a 30 minute warm-up period to ensure accurate
performance. |
Connect all test equipment as shown.
Connect GPIB cables to all GPIB-controlled test equipment.
While performing this adjustment, follow all instructions on the controller display.
Power Meter and Power Sensor Calibration
Attenuator Calibration (Steps ≤30 dB)
Attenuator Calibration >30 dB (Frequencies ≤3000 MHz)
Attenuator Calibration >30 dB (Frequencies >3000 MHz)
